Story highlights

The cause of Sunday's power outage at the Super Bowl in New Orleans has been traced to a newly installed electrical relay device meant to protect Superdome equipment, a power company and the device's manufacturer said Friday.

But the companies appear to be on different pages about whether human error was to blame.

The relay, put online late last year, triggered unexpectedly, causing another device to stop supplying power to part of the building, Entergy New Orleans told city officials Friday.

The partial outage interrupted the game between the Baltimore Ravens and the San Francisco 49ers for about 35 minutes, and city officials have been anxious about whether the outage will impact the city's efforts to attract future big-ticket events.

Entergy told New Orleans City Council members that the company still doesn't know why the device triggered, but the relay has been removed, the dome's electrical system is ready to go and steps will be taken to ensure a malfunction doesn't happen again.

2013 Super Bowl: The best photos – Morgan Cox of the Baltimore Ravens lies on the field while celebrating after defeating the San Francisco 49ers 34-31 in Super Bowl XLVII at the Mercedes-Benz Superdome on Sunday, February 3, in New Orleans, Louisiana.

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2013 Super Bowl: The best photos – Super bowl MVP Joe Flacco of the Baltimore Ravens celebreates with his teammates.

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2013 Super Bowl: The best photos – Head coach John Harbaugh of the Baltimore Ravens, left, shakes hands with his brother, head coach Jim Harbaugh of the San Francisco 49ers, after winning Super Bowl XLVII in a close contest.

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2013 Super Bowl: The best photos – Retiring linebacker Ray Lewis of the Baltimore Ravens celebrates as confetti falls after the game.

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2013 Super Bowl: The best photos – Perrish Cox of the San Francisco 49ers kneels on the sideline after his team lost the Super Bowl to the Baltimore Ravens.

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2013 Super Bowl: The best photos – Ed Reed of the Baltimore Ravens hoists the Vince Lombardi Trophy after the win.

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2013 Super Bowl: The best photos – Quarterback Joe Flacco is tackled by teammates while celebrating after the game.

2013 Super Bowl: The best photos – 49ers quarterback Colin Kaepernick walks off the field after the game.

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2013 Super Bowl: The best photos – Bobbie Williams of the Baltimore Ravens, right, and his teammates celebrate their win against the San Francisco 49ers.

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2013 Super Bowl: The best photos – Confetti falls on the field as the Ravens celebrate their 34-31 victory over the 49ers.

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2013 Super Bowl: The best photos – Cornerback Perrish Cox of the San Francisco 49ers kneels down among the confetti following his team's loss.

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2013 Super Bowl: The best photos – Vonta Leach, left, and Ray Lewis of the Baltimore Ravens celebrate on the field after the game.

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2013 Super Bowl: The best photos – Michael Crabtree of the San Francisco 49ers fails to make a catch in the end zone late in the fourth quarter against Ed Reed of the Baltimore Ravens.

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2013 Super Bowl: The best photos – Ray Lewis, left, and Ed Reed of the Baltimore Ravens celebrate after the San Francisco 49ers couldn't convert on a fourth down play in the final two minutes of the fourth quarter.

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2013 Super Bowl: The best photos – Michael Oher of the Ravens lifts teammate Arthur Jones into the air as the clock runs out.

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2013 Super Bowl: The best photos – Patrick Willis of the San Francisco 49ers makes contact with Bernard Pierce of the Baltimore Ravens.

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2013 Super Bowl: The best photos – Joe Flacco of the Baltimore Ravens throws a pass in the fourth quarter against the San Francisco 49ers.

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2013 Super Bowl: The best photos – Quarterback Colin Kaepernick of the 49ers scores a 15-yard rushing touchdown in the fourth quarter against the Ravens.

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2013 Super Bowl: The best photos – Anquan Boldin of the Baltimore Ravens stiff-arms Chris Culliver of the San Francisco 49ers after catching a 30-yard pass in the third quarter.

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2013 Super Bowl: The best photos – Ravens quarterback Joe Flacco throws a pass against the San Francisco 49ers during Super Bowl XLVII.

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2013 Super Bowl: The best photos – Ray Lewis of the Baltimore Ravens watches from the bench during the third quarter.

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2013 Super Bowl: The best photos – Ted Ginn Jr., left, of the San Francisco 49ers celebrates with teammate Dashon Goldson after a long punt return.

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2013 Super Bowl: The best photos – Bernard Pierce of the Baltimore Ravens is tackled by Dashon Goldson of the 49ers.

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2013 Super Bowl: The best photos – Arthur Jones of the Baltimore Ravens celebrates after a tackle during Super Bowl XLVII.

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2013 Super Bowl: The best photos – Tarell Brown of the San Francisco 49ers causes Ray Rice of the Baltimore Ravens to fumble in the third quarter; Brown recovered the fumble.

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2013 Super Bowl: The best photos – Frank Gore of the 49ers runs in for a touchdown in the third quarter past Corey Graham of the Ravens.

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2013 Super Bowl: The best photos – Frank Gore, left, and Colin Kaepernick of the 49ers celebrate after Gore scored a 6-yard rushing touchdown in the third quarter.

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2013 Super Bowl: The best photos – Running back Frank Gore of the San Francisco 49ers celebrates with quarterback Colin Kaepernick after scoring a touchdown in the third quarter.

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2013 Super Bowl: The best photos – Frank Gore of the 49ers celebrates his 6-yard rushing touchdown in the third quarter.

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2013 Super Bowl: The best photos – Michael Crabtree of the 49ers scores on a touchdown pass in the third quarter against the Baltimore Ravens.

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2013 Super Bowl: The best photos – Ted Ginn Jr. of the 49ers returns a punt 32 yards against Sam Koch of the Ravens.

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2013 Super Bowl: The best photos – 49er fans react as they watch Super Bowl XLVII at Gold Dust Lounge in San Francisco.

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2013 Super Bowl: The best photos – Anquan Boldin of the Baltimore Ravens attempts to catch a pass in front of Chris Culliver, center, and Dashon Goldson of the San Francisco 49ers.

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2013 Super Bowl: The best photos – Michael Crabtree of the San Francisco 49ers runs into the end zone on a 31-yard touchdown reception in the third quarter.

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2013 Super Bowl: The best photos – Terrell Suggs of the Baltimore Ravens paces on the field during the power outage.

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2013 Super Bowl: The best photos – The San Francisco 49ers wait for all the power to come back to the Superdome.

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2013 Super Bowl: The best photos – Quarterback Joe Flacco and Baltimore Ravens teammates wait on the field as a third-quarter power outage brings Super Bowl XLVII to a temporary halt.

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2013 Super Bowl: The best photos – The Ravens' cheerleaders perform on the sidelines during the power outage.

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2013 Super Bowl: The best photos – A sudden power outage at the Mercedes-Benz Superdome causes a 34-minute delay early in the third quarter.

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2013 Super Bowl: The best photos – Jacoby Jones of the Baltimore Ravens, No. 12, does "the Ray Lewis dance" to celebrate his 108-yard kickoff return for a touchdown at the start of the third quarter.

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2013 Super Bowl: The best photos – Ravens kick returner Jacoby Jones celebrates his touchdown at the start of the second half.

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2013 Super Bowl: The best photos – Jacoby Jones of the Baltimore Ravens runs the second-half kickoff back 108 yards for a touchdown.

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2013 Super Bowl: The best photos – Jacoby Jones of the Baltimore Ravens returns the second-half kickoff 108 yards for a record-tying touchdown.

2013 Super Bowl: The best photos – Donte Whitner of the San Francisco 49ers commits a face mask penalty against Ed Dickson of the Baltimore Ravens in the second quarter.

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2013 Super Bowl: The best photos – Ray Rice of the Baltimore Ravens runs the ball against the 49ers.

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2013 Super Bowl: The best photos – Arthur Jones of the Baltimore Ravens celebrates after recovering a fumble from LaMichael James of the San Francisco 49ers in the second quarter of Super Bowl XLVII.

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2013 Super Bowl: The best photos – Courtney Upshaw of the Ravens forces LaMichael James of the 49ers to fumble in the second quarter.

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2013 Super Bowl: The best photos – Quarterback Joe Flacco of the Ravens attempts to escape pressure from Ahmad Brooks of the 49ers.

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2013 Super Bowl: The best photos – Ravens quarterback Joe Flacco scrambles out of the pocket against the 49ers.

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2013 Super Bowl: The best photos – Bernard Pollard of the Baltimore Ravens tries to tackle Vernon Davis of the San Francisco 49ers.

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2013 Super Bowl: The best photos – Quarterback Colin Kaepernick of the 49ers rolls out of the pocket and looks to pass during the second quarter.

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2013 Super Bowl: The best photos – Vernon Davis of the San Francisco 49ers goes airborne after catching a pass against the Baltimore Ravens in the first quarter of Super Bowl XLVII at the Mercedes-Benz Superdome in New Orleans, Louisiana, on Sunday, February 3.

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2013 Super Bowl: The best photos – David Akers of the San Francisco 49ers kicks a 36-yard field goal in the first quarter.

2013 Super Bowl: The best photos – Anquan Boldin of the Baltimore Ravens makes a 13-yard touchdown reception in the first quarter against the San Francisco 49ers during Super Bowl XLVII at the Mercedes-Benz Superdome on Sunday, February 3, in New Orleans, Louisiana.

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2013 Super Bowl: The best photos – Ravens wide receiver Anquan Boldin brings the ball down in the end zone.

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2013 Super Bowl: The best photos – Donte Whitner of the 49ers tries to defend Anquan Boldin of the Ravens.

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2013 Super Bowl: The best photos – Quarterback Colin Kaepernick of the San Francisco 49ers drops back to pass in the first quarter against the Baltimore Ravens.

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2013 Super Bowl: The best photos – Justin Tucker of the Baltimore Ravens kicks the ball to the San Francisco 49ers to start Super Bowl XLVII.

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2013 Super Bowl: The best photos – Alicia Keys sings the National Anthem before the start of Super Bowl XLVII.

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2013 Super Bowl: The best photos – Alicia Keys reaches into the air during her rendition of the National Anthem.

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2013 Super Bowl: The best photos – Children in the Sandy Hook Elementary School Chorus walk off the field after singing "America The Beautiful" prior to Super Bowl XLVII.

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2013 Super Bowl: The best photos – The Sandy Hook Elementary School Chorus stands on the field for their performance of "America the Beautiful."

2013 Super Bowl: The best photos – Dancers perform on the field before the start of Super Bowl XLVII.

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2013 Super Bowl: The best photos – 49ers mascot Sourdough Sam waves a flag on the field as players take the field shortly before kickoff.

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2013 Super Bowl: The best photos – Quarterback Joe Flacco of the Baltimore Ravens stands on the field prior to kickoff against the San Francisco 49ers.

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2013 Super Bowl: The best photos – Ravens cheerleaders stand on the sidelines before Sunday night's game against the 49ers.

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2013 Super Bowl: The best photos – The Southern University Marching Band gets ready to perform before the start of Super Bowl XLVII.

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2013 Super Bowl: The best photos – Quarterback Colin Kaepernick of the San Francisco 49ers warms up on the field prior to the Super Bowl.

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2013 Super Bowl: The best photos – Head coach John Harbaugh of the Baltimore Ravens hugs linebacker Ray Lewis prior to the start of Super Bowl XLVII against the San Francisco 49ers.

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2013 Super Bowl: The best photos – Baltimore Ravens players gather around team leader Ray Lewis as he leads them in a rally on the field just before the start of the game.

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2013 Super Bowl: The best photos – Ray Lewis of the Baltimore Ravens warms up on field before the start of Super Bowl XLVII against the San Francisco 49ers.

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2013 Super Bowl: The best photos – Head coach Jim Harbaugh works with quarterback Colin Kaepernick of the San Francisco 49ers during warm-ups prior to the game.

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2013 Super Bowl: The best photos – Head coach Jim Harbaugh, right, of the San Francisco 49ers shakes hands with his brother, head coach John Harbaugh of the Baltimore Ravens, prior to the start of Super Bowl XLVII.

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2013 Super Bowl: The best photos – A Baltimore Ravens fan wears his heart on his scalp in New Orleans.

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2013 Super Bowl: The best photos – O.J. Brigance, left, senior player development adviser for the Baltimore Ravens, makes his way across the field with his wife, Chanda, prior to the start of Super Bowl XLVII. Brigance, a former Ravens player, was diagnosed with Lou Gehrig's disease in 2007.

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2013 Super Bowl: The best photos – A 49ers fan is weighed down with team paraphernalia poses outside the Superdome before the start of the game.

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2013 Super Bowl: The best photos – 49ers fans cheer for their team from the stands during pre-game warm-ups.

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2013 Super Bowl: The best photos – Super Bowl programs are sold outside the stadium as fans stream into the Superdome.

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2013 Super Bowl: The best photos – San Francisco fans Shane Knight, left, and Jimmy Bowers are hoping the 49ers earn another ring.

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EXPAND GALLERY

But the relay's manufacturer, Chicago-based S&C Electric Co., says it believes it knows why the problem happened: The relay, it says, wasn't operated at the proper setting.

System operators essentially put the relay's trip setting too low, S&C vice president Michael Edmonds wrote to CNN in an e-mail. The electrical load exceeded the trip setting, so the relay triggered, he said.

That activated the switch gear, which is designed to cut some power to isolate any problem and prevent system damage and a larger outage.

"Based on the onsite testing, we have determined that if higher settings had been applied, the equipment would not have disconnected the power," Edmonds wrote. "S&C continues to work with all those involved to get the system back online, and our customers can continue to rely on the quality and performance of our products."

"Tests conducted by S&C and Entergy on the two relays installed at the Superdome shows that one relay functioned as expected and the other relay did not.

"We will continue to do more testing but we believe that we have zeroed in on the device that caused the outage, and we have removed it from service."

S&C was not represented at the council committee meeting in New Orleans.

The company that manages the dome, SMG, told the panel it concurred that the device is linked to the power outage.

But the explanation won't end the issue for some officials, as Councilwoman Jackie Clarkson pressed Rice to allow an independent audit.

Rice didn't commit, instead replying that a third-party inspector will be used if Entergy and SMG determine one is needed.

The relay and switch gear were part of Entergy's 2011-2012 project to improve electrical reliability at the dome, Entergy official Dennis Dawsey told council members.

The relay device wasn't put online until December 21. Between then and the Super Bowl, the device functioned properly during three major events -- the New Orleans Bowl, a Saints-Panthers NFL game, and the Sugar Bowl -- Entergy said.

Rice said the company would work closely with the device's manufacturer to determine what caused the device to trigger when it shouldn't have.

"We are going to do everything humanly possible (to ensure) we do not experience an event like this again," Rice said.

An SMG official emphasized to the panel that the power failure had nothing to do with SMG's recent efforts to replace the cables that feed electricity from Entergy's connection points to the dome.

The Louisiana Stadium and Exposition District, a state agency that oversees the Superdome, had approved spending hundreds of thousands of dollars to replace the feeder cables. The SMG official said Friday that the cables were replaced because they were 15 years old, and that SMG doesn't "see any way (the cables) were involved in this."

The electrical outage at the Superdome set off a storm of social media amusement among viewers and inspired advertising tweets with blackout twists.

Carmaker Audi took a swipe at its competitor, tweeting that it was sending "LED lights" over to the dome, which is officially named the Mercedes-Benz Superdome.

But for the picturesque Super Bowl host city -- perpetually concerned with its reputation, especially since Hurricane Katrina -- the power failure broadcast to the world was a huge embarrassment.

Mayor Mitch Landrieu promised that night there would be answers soon.

Clarkson, pressing for a third-party examination of the cause, emphasized that the city intends to bid for the 2018 Super Bowl.

"We are in contention for 2018," Clarkson said. "(An outside test) is clearly imperative ... to defy the naysayers that could be arising around the country to say that we shouldn't have this (Super Bowl)."